The company has also embarked on closer, information-sharing partnerships with other tech companies like Twitter, Google and Microsoft.

Three of the disinformation campaigns originated in Iran and one in Russia, Facebook said, with state-backed actors disguised as genuine users.

The campaigns were aimed at people in North Africa, Latin America and the United States, the company said.

The posts crossed categories and ideological lines, seemingly with no specific intent other than to foment discord.

Some of the posts touched on conflict in the Middle East, while others pointed to racial strife and some invoked Alexandria Ocasio-Cortez, a Democratic congresswoman from New York, according to examples provided by Facebook.

East 17 Torrent Professional Troll Farm

In that campaign, 50 accounts linked to Russias Internet Research Agency a Kremlin-backed professional troll farm targeted candidates for the Democratic presidential nomination including former Vice President Joseph R.

Biden Jr. and Senators Bernie Sanders and Elizabeth Warren, according to an analysis from Graphika, a social media research firm.

Roughly half of those accounts claimed to be based in swing states.

The Internet Research Agency was also responsible for targeting the American electorate during the 2016 presidential election.

Facebook said that it did not allow coordinated inauthentic behavior and said it would be more transparent about where posts were coming from and would better verify the identities of those putting up messages and ads.

Among other measures, the company rolled out new features on Monday to label whether posts were coming from state-sponsored media outlets.

The revelations of the new disinformation campaigns highlight the difficulties that Facebook faces with its stance on free expression, a position that its chief executive, Mark Zuckerberg, emphasized last week.

In a speech at Georgetown University on Thursday, Mr.

Zuckerberg extolled the virtues of unfettered expression and how everyone should have a voice on the social network.

But that approach has opened the door for foreign operatives and others to spread conspiracy theories, inflammatory messages and false news through Facebook.

In a conference call on Monday about the disinformation campaigns and election security measures, Mr.

Zuckerberg said his company was better equipped to handle false information on the site now.

Elections have changed significantly since 2016, but Facebook has changed too, he said.

Weve gone from being on our back foot to now proactively going after some of the biggest threats that are out there.

East 17 Torrent Torrent Of Criticism

Facebook has been under pressure amid a near-daily torrent of criticism from American presidential candidates, the public, the media and regulators around the world, many of whom argue that the company is unable to properly corral its outsize power.

Ms. Warren, a front-runner for the Democratic presidential nomination, recently accused Facebook of being a disinformation-for-profit machine because it allowed false information from political leaders to circulate under its free-speech stance.

The Federal Trade Commission and the Justice Department are investigating Facebooks market power and history of technology acquisitions.

To combat the critics, Mr.

Zuckerberg has ramped up his public appearances.

He recently gave several interviews to conservative and liberal media outlets, in addition to his robust defense of his companys policies at Georgetown University.

On Wednesday, he will again be in the spotlight when he is scheduled to testify before congressional lawmakers about Facebooks troubled cryptocurrency effort, called Libra.

Image Last week, Mark Zuckerberg, Facebooks chief executive, defended his companys stance on free expression.

Credit. Justin T.

Gellerson for The New York Times In the conference call on Monday, Mr.

Zuckerberg said Facebook had become better able to seek out and remove foreign influence networks, relying on a team of former intelligence officials, digital forensics experts and investigative journalists.